The hydroxy analogue of methionine is a well-known chemical compound which is otherwise described as .alpha.-hydroxgy-.gamma.-methylmercaptobutyric acid (MHBA). This compound has nutrient values equivalent to the corresponding amino acid, methionine. The calcium salt of MHBA is also well known, and it is usually in this form that it is used to fortify animal feeds.
In commonly used processes for preparing the calcium salt of MHBA, it has been necessary to isolate the product calcium salt from dilute aqueous solutions. This is done by evaporation of the water to give a slurry of the product calcium salt which is then isolated by filtration and drying. (U.S. Pat. Nos. 2,745,745 and 3,175,000). In applicants' experience, it has often been necessary to evaporate ten to sixteen pounds of water for each pound of product produced. This evaporation step is costly and is becoming even more so as energy costs rise. There is therefore a clear need for a new, economical, and energy-efficient process for preparing this useful feed supplement.